Talk

And speaking of personalized medicine and genetic testing for drug response…

The FDA recently recommended that people have genetic testing for HLA-B*5701 before taking the AIDS drug, abacavir (brand-name Ziagen). This test can identify people who carry a genetic marker that is associated with life-threatening hypersensitivity reactions.

Right now, abacavir hypersensitivity reaction occurs in around 8% of patients, and shows up within the first six weeks of therapy.

“The guideline change represents one of the first situations in which a genetic test has been recommended for use in clinical practice to guide drug selection that will affect treatment decisions for thousands of patients each year,” says Dr. Bruce R. Schackman, associate professor of public health and chief of the Division of Health Policy in the Department of Public Health at Weill Cornell Medical College. Dr. Shackman is the lead author of a new study that evaluated the cost-effectiveness of genetic testing for abacavir hypersensitivity.

Abacavir is often used in “cocktails” with other antiretrovirals, including Epzicom and Trizivir.

From FDA’s materials for healthcare professionals:

Information for Patients to Consider if they are taking Abacavir:

• Some people are at greater risk for serious allergic reactions when first starting treatment with abacavir or with medications containing abacavir in a combination medicine. We can test for a risk factor for such reactions, which is called HLA-B*5701, before giving abacavir. Tests for HLA-B*5701 are readily available.
• If you test positive for HLA-B*5701, then your doctor will take that into account for your medical care.
• If you test negative for HLA-B*5701, you are at lower risk of a serious allergic reaction when taking abacavir, but it could still occur, and you still should be watchful.
• Even if you have previously taken abacavir without a reaction before but have never been tested for HLA-B*5701, you should still be tested before taking abacavir again.
• If you and your doctor decide that the benefits of starting abacavir outweigh possible risks, then you should watch for any sign described on the warning card. Abacavir HSR may include a combination of the following symptoms: fever, rash, generally ill feeling, extreme tiredness or achiness, gastrointestinal symptoms (nausea, vomiting, diarrhea or stomach pain), and respiratory symptoms (shortness of breath, cough or sore throat). If you develop a combination of any of the symptoms or signs of a reaction that are listed above, then you should contact your doctor immediately.

According to statistics from the Centers for Disease Control and Research, there are 233,079 HIV-infected people in the U.S., and 448,871 people were living with AIDS at the end of 2006. Between 5% and 8% of HIV-infected patients are positive for HLA-B*5701.

• To see the full FDA Label for Abacavir and other info from FDA for medical professionals: go to this page and click on the second link, “Prescribing (Label) Information from Drugs@FDA”
• If you are looking for HLA-B*5701 testing, DNA Direct can coordinate testing for you and your doctor: call our Clinical Services Department at 1-877-646-0222 or email expert@dnadirect.com.

This entry was posted on Friday, September 19th, 2008 at 1:41 pm and is filed under Drug Response, Personalized Medicine. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.